Preheat your oven to 425°F and line a large rimmed baking sheet with parchment paper.
Cut the chicken breast into bite-sized pieces and place them in a large mixing bowl along with the cauliflower florets.
Sprinkle the arrowroot starch, sea salt, and black pepper over the chicken and cauliflower, tossing thoroughly until every piece is lightly dusted.
Spread the mixture in a single layer on the prepared baking sheet, ensuring there is space between pieces for optimal crisping.
Roast in the oven for 20 minutes, flipping halfway through, until the cauliflower is tender and the chicken is cooked through with golden edges.
While the tray is roasting, whisk together the melted ghee and buffalo hot sauce in a small bowl until emulsified.
Prepare the ranch dip by combining the Greek yogurt, dried dill, garlic powder, onion powder, and lemon juice in a small ramekin, stirring until smooth.
Remove the baking sheet from the oven and drizzle the buffalo-ghee mixture over the roasted chicken and cauliflower, tossing gently to coat.
Return the tray to the oven for an additional 5 minutes to allow the sauce to glaze and set.
Serve the crispy buffalo mixture immediately with the chilled creamy ranch dip on the side.